Remove dart:codec and move classes into dart:convert.

sdk/lib/convert/json.dart

Index: sdk/lib/convert/json.dart
diff --git a/sdk/lib/convert/json.dart b/sdk/lib/convert/json.dart
index 8baf9970bbfc9b630f71897779c686ba6dafd4cb..f29517eb5d04f074561c7af98cffece8ba80ea26 100644
--- a/sdk/lib/convert/json.dart
+++ b/sdk/lib/convert/json.dart
@@ -4,6 +4,56 @@
 
 part of dart.convert;
 
+final JSON = new JsonCodec();
+
+/**
+ * A [JsonCodec] encodes JSON objects to strings and decodes strings to
+ * JSON objects.
+ */
+class JsonCodec extends Codec<Object, String> {
+  const JsonCodec();
+
+  /**
+   * Creates a `JsonCodec` with the given reviver.
+   *
+   * The [reviver] function is called once for each object or list property
+   * that has been parsed during decoding. The `key` argument is either the
+   * integer list index for a list property, the map string for object
+   * properties, or `null` for the final result.
+   */
+  factory JsonCodec.withReviver(reviver(var key, var value)) =
+      _ReviverJsonCodec;
+
+  /**
+   * Parses the string and returns the resulting Json object.
+   *
+   * The optional [reviver] function is called once for each object or list
+   * property that has been parsed during decoding. The `key` argument is either
+   * the integer list index for a list property, the map string for object
+   * properties, or `null` for the final result.
+   *
+   * The default [reviver] (when not provided) is the identity function.
+   */
+  Object decode(String str, {reviver(var key, var value)}) {
+    return new JsonDecoder(reviver).convert(str);
+  }
+
+  JsonEncoder get encoder => new JsonEncoder();
+  JsonDecoder get decoder => new JsonDecoder(null);
+}
+
+class _ReviverJsonCodec extends JsonCodec {
+  final Function _reviver;
+  _ReviverJsonCodec(this._reviver);
+
+  Object decode(String str, {reviver(var key, var value)}) {
+    if (reviver == null) reviver = _reviver;
+    return new JsonDecoder(reviver).convert(str);
+  }
+
+  JsonDecoder get decoder => new JsonDecoder(_reviver);
+}
+
 /**
  * A [JsonEncoder] converts JSON objects to strings.
  */